In his latest research, Grossman, along with postdoc Xining Zang, research scientist Nicola Ferralis, and five others, found ways to use coal, tar, and pitch to produce thin coatings with highly controllable and reproducible electrical conductivity, porosity, and other properties. Using a laser, they were able make prototype devices from the inexpensive, ubiquitous materials, including a supercapacitor to store electricity, a flexible strain gauge, and a transparent heater.

http://news.mit.edu/2020/carbon-coal-tar-high-tech-0427